The present invention relates to fibrous monolith composites that provide increased flaw insensitivity, improved hardness, wear resistance, and damage tolerance for use in dynamic environments to mitigate impact damage to, and/or increase the wear resistance of, structures comprising such materials.
Certain carbides, nitrides, borides, oxides, and suicides exhibit enhanced mechanical properties, including damage tolerance and wear resistance. As a result, these materials have found use in dynamic environments where the materials are subject to harsh conditions, such as increased wear, thermal shock, elevated temperatures and the like. For example, many of the carbides, nitrides, borides, oxides, and silicides of the elements from Groups IVb, Vb, and VIb of the periodic table, as well as carbides, nitrides, borides, oxides, and silicides of boron, aluminum, and silicon have been used in industrial and other applications where such conditions are likely to be encountered. Generally, structures formed of these materials exhibit improved strength and hardness at ambient and elevated temperatures, improved toughness and wear resistance, high melting points, thermal shock resistance, and oxidation resistance.
These materials have found use in the fabrication of structures that may be subject to impact damage by foreign objects, which is commonly referred to as foreign object damage (FOD), such as in turbomachinery and turbine engine applications. These materials also may be used for the fabrication of tools, inserts and other implements that may be subject to wear impact damage, such as in mining, construction, machining and similar industrial applications. For example, because of their abrasive and impact wear resistance properties, materials formed of carbides, nitrides, borides, oxides, and silicides have been used in mining applications where, for example, extremely severe wear conditions and impact loadings may be encountered by the drill bits during rock crushing and removal. Additionally, because of their ability to withstand high temperatures, these materials also have been used in machining applications where very high localized temperatures may be encountered adjacent the cutting edge of the tool.
The usefulness of such materials, however, has been limited by a lack of wear resistance, damage tolerance and fracture toughness exhibited by the materials. As a result, structures fabricated from these materials tend to wear and/or fracture more quickly than is desired. The need for frequent replacement of parts is costly and results in down time that is both time consuming and costly.
There remains a need for materials exhibiting improved hardness, strength, wear resistance and fracture toughness, as compared to presently known materials, for use in dynamic environments to mitigate impact damage to, and/or increase the wear resistance of, structures comprising such materials.
The present invention relates to structures that include unique architectural arrangements of fibrous monolith (xe2x80x9cFMxe2x80x9d) composites to provide the structures with increased flaw insensitivity, increased wear resistance, and damage tolerance. The present invention also relates to methods of fabricating such composites and structures.
The composites of the present invention may be used as coatings for existing structures to mitigate impact damage in dynamic environments and to reduce wear on the structures, as the composites demonstrate very high fracture energies, increased flaw insensitivity, increased wear resistance, and increased damage tolerance. Additionally, a more substantial portion of, or even a complete, structure may be formed from the FM composites, thereby extending the benefits obtained with use of the FM composites.